But, as we all know, the spring of 2012 has been anything but typical.

March averaged 8.4 degrees above normal, forcing many trees and plants to bloom several weeks ahead of schedule. April hasn’t been much different, averaging 6.4 degrees above normal.

Typically, experts suggest waiting until the second week of May to plant any tender vegetation in your backyard gardens, but no doubt the mild weather has tricked many folks into jumping the gun.

Now there is concern not just for tonight but for the next several nights that temperatures will drop to dangerously low levels, threatening not just outdoor plants but fruit trees as well.

We spoke with Mark Parlee, owner of Parlee Farms in Tyngsboro and he is pulling out all the stops to protect his orchard.

He tells us that just about all of his fruit trees and plants are in full bloom (apples, blueberries, strawberries). Keep in mind that full bloom doesn’t mean the fruit is fully formed, it simply means the bud has fully flowered and this is the most vulnerable stage in the bud to flower to fruit process.

Mark is eyeing a temperature threshold of about 28-29 degrees. Anything near or below that could mean significant damage to the vulnerable fruit trees. For that reason Mark and many other local farmers will not be getting much sleep over the next several nights.

Instead, they will be monitoring temperature conditions hour-by-hour and then irrigating when the temperatures drop below critical values. This could mean watering about 60 gallons per minute, per acre. I wouldn’t want to see that water bill!

Watering may seem counter intuitive on a freezing night, but it actually will save and protect most of the crops.

As water turns to ice, it releases heat in the process. This release of heat helps to keep the plants surface right near the freezing mark. It is a delicate balance of just the right amount of water and with dozens of overhead sprinklers, Mark has to constantly check each one to be sure it doesn’t ice over, making for a very long, cold night.

Homeowners should be equally concerned for their outdoor plants and should either cover or bring inside any tender vegetation. While some of the more hardy plants should fare fine (pansies, cold crop veggies), many others will not and all precautions should be taken.

So is there a chance that temps wont fall that low?

Yes.

The wind will be the key tonight. When winds are busy, over 10 mph, that will typically keep the air well mixed and prevent a big drop in temperature.